The eBioC1.7 monoclonal antibody reacts with human CD244 (2B4, p38). In human, CD244 is a 38kDa protein expressed on NK cells, a subset of CD8+ T cells, γδ T cells, monocytes, basophils and eosinophils. Binding of the CD244 ligand, CD48, results in NK cell activation, unlike mouse CD244, which is an inhibitory receptor. For CD244 expressed on NK cells, binding of CD48 results in enhanced NK cell cytotoxicity and secretion of IFN-γ. Recently, it was demonstrated that binding of the C1.7 monoclonal antibody and CD48 involve the same residue in the V domain of human CD244, which explains the ability of C1.7 binding to induce activation of NK cells. Binding of C1.7 to CD244 leads to tyrosine phosphorylation and recruitment of the adaptor molecule SAP (SLAM-associated protein). Patients with X-linked lymphoproliferative disorder (XLPD) have a mutation in SAP which renders it unable to bind to phosphorylated CD244.